From: Jonathan ZD (Nuvo25@hotmail.com)
Date: Sat Jan 29 2005 - 13:55:12 GMT-3
The Address Structure for "Site-Local Unicast Address" is :
1st 10-bit : Site-Local unicast address identification (1111 1110 11 = FEC0)
2nd 38-bit : All Zero
3nd 16-bit (another word - last 16-bit of the 1st 64-bit of the address) :
SLA (Site-Level Aggregator)
Last 64-bit: Inteface-ID (Auto Generated by converting interface physical
address (mac-address) into EUI-64 format)
Therefore, for the requirement, the address should be in the form of:
FEC0: :A:X:X:X:X
Where X:X:X:X: part is the auto-generated interface-id.
*** The Address Structure - Refer to the section "3.1 Aggregatable Global
Unicast Address Structure" from RFC 2374
*** The SLA (Site-Level Aggregator) - Refer to the section "3.5 Site-Level
Aggregation Identifier" from RFC 2374
The answer from your work book kinda confuse me too.
1) I don't know that they mean by "site-local subnet 7B", and why that
address (7B) appear in the last 16 octect of the Interface-id??? For me,
site-local subnet should be part of SLA.
2) For Site-Local address, I believe that we (users) can only manipulate the
SLA part of the address, the last 64-bit of the address (interface-id)
should be generated by the router, so I don't understand how DOiT put "7B"
under interface-id part of the address.
3) What they mean by "X" under the address???
----- Original Message -----
From: <my-ccie-test@libero.it>
To: <ccielab@groupstudy.com>
Sent: Saturday, January 29, 2005 7:12 AM
Subject: IPv6 Addressing
> Hi guys,
> I'm just started to study for my ccie lab test.
> I'm studing on Netmasterclass DOiT.
> it says in IPV6 topic:
>
> configure site-local subnet 7B on R1,R2,R3. Use SLA number A for this part
of the network.
> DOiT says the address is FEC0:0:0:A::7B:"x"/125
> I'm confused about subnet-id and SLA number.
>
> I read on RFC 3513:
>
> Site-Local addresses have the following format:
>
> | 10 |
> | bits | 54 bits | 64 bits |
> +----------+-------------------------+----------------------------+
> |1111111011| subnet ID | interface ID |
> +----------+-------------------------+----------------------------+
>
> Site-local addresses are designed to be used for addressing inside of
> a site without the need for a global prefix. Although a subnet ID
> may be up to 54-bits long, it is expected that globally-connected
> sites will use the same subnet IDs for site-local and global
> prefixes.
>
> Routers must not forward any packets with site-local source or
> destination addresses outside of the site.
>
>
> It shows only subnet-id
> So, wath is SLA number?
> Why it doesn't show "7B" in the subnet-id field?
>
>
> thanks
>
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